On a machine, a driving shaft is rotating in a direction continuously and a driven shaft can make rotation in the normal direction or reverse direction instantaneously upon receipt of signal without changing the rotation direction of the driving shaft, then, a direction changing rotation mechanism has to be installed between the driving shaft and the driven shaft. For example, a mechanism which has to carry fast reciprocating curvilinear or linear movement of unequal distance within an unfixed range without changing the rotation direction of motor.